Civilization IV is a reinvention of the historical turn- based strategy game series. All the basic concepts from the previous games are still here, but many of the more troublesome elements have been improved. City production, combat and culture have all been tweaked to allow for a more intuitive application.

Culture, sort of controversial in the previous game, is much more refined this time. A city culturally more defined will also be harder for a rival to take over by force. Although religion is tied closely to culture, it's a separate concept in civilization. The missionaries, temples and holy cities of each religion function exactly in the same way; only the names are different. You gain access to new religions and new infrastructural facilities by researching the appropriate technology.

Each unit that wins a fight earns experience points that can be used to buy promotions. These range from simple bonuses to the ability to heal units. The game still suffers from the spearman-defeats-tank combats. Though the inequality between primitive and advanced units isn't quite as wide as in the 'real world,' it is acceptable, though at times it may seem far-fetched that knights can defeat helicopters.

Winning isn't easy. The AI presents a wide range of challenges, depending on your difficulty level. You'll notice that each AI comes with its own strengths. They are much more active in terms of conducting trade this time round and frequently offer exchanges all on their own.

Previous versions of Civilization haven't been ideally suited to online play. The turn-based format took a lot of time to download. Happily, Civilization IV has improved much in that section.

Anyway, creating, finding and joining a game are just about as easy as it could get, and the Game Spy technology seems reliable enough. From elephants walking around to spearmen jabbing at wolves, the visual effects are fantastic. You'll see plenty of unique combat animations as you play through the game.

The music really steals the show. Also, hats off to Leonard Nimoy for his amazing voiceover including reading short quotations as each new technology is discovered. The quotations are well chosen and really help to connect the progress you're making in the game to our own history. Although the new interface is wonderful, there are a few areas where more could be done. The announcements that your rivals have founded a new religion should have been highlighted. Civilization IV reenergises the core concepts of the series and creates an original game. Die-hard fans will definitely find that the game offers much more variety this time round.